# -*- coding: utf-8 -*-
# Copyright (c) 2014-2017 Claudiu Popa <pcmanticore@gmail.com>
# Copyright (c) 2014 Michal Nowikowski <godfryd@gmail.com>
# Copyright (c) 2014 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr>
# Copyright (c) 2015 Pavel Roskin <proski@gnu.org>
# Copyright (c) 2015 Ionel Cristian Maries <contact@ionelmc.ro>
# Copyright (c) 2016-2017 Pedro Algarvio <pedro@algarvio.me>
# Copyright (c) 2016 Alexander Todorov <atodorov@otb.bg>
# Copyright (c) 2017 Łukasz Rogalski <rogalski.91@gmail.com>
# Copyright (c) 2017 Mikhail Fesenko <proggga@gmail.com>
# Copyright (c) 2018 Mike Frysinger <vapier@gmail.com>
# Copyright (c) 2018 Sushobhit <31987769+sushobhit27@users.noreply.github.com>
# Copyright (c) 2018 Anthony Sottile <asottile@umich.edu>

# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
# For details: https://github.com/PyCQA/pylint/blob/master/COPYING

"""Checker for spelling errors in comments and docstrings.
"""

import os
import tokenize
import re

try:
    import enchant
    from enchant.tokenize import (get_tokenizer,    # type: ignore
                                  Chunker,
                                  Filter,
                                  EmailFilter,
                                  URLFilter,
                                  WikiWordFilter)
except ImportError:
    enchant = None
    # pylint: disable=no-init
    class Filter:  # type: ignore
        def _skip(self, word):
            raise NotImplementedError

    class Chunker:  # type: ignore
        pass


from pylint.interfaces import ITokenChecker, IAstroidChecker
from pylint.checkers import BaseTokenChecker
from pylint.checkers.utils import check_messages

if enchant is not None:
    br = enchant.Broker()
    dicts = br.list_dicts()
    dict_choices = [''] + [d[0] for d in dicts]
    dicts = ["%s (%s)" % (d[0], d[1].name) for d in dicts]
    dicts = ", ".join(dicts)
    instr = ""
else:
    dicts = "none"
    dict_choices = ['']
    instr = " To make it working install python-enchant package."


class WordsWithDigigtsFilter(Filter):
    """Skips words with digits.
    """

    def _skip(self, word):
        for char in word:
            if char.isdigit():
                return True
        return False


class WordsWithUnderscores(Filter):
    """Skips words with underscores.

    They are probably function parameter names.
    """
    def _skip(self, word):
        return '_' in word


class CamelCasedWord(Filter):
    r"""Filter skipping over camelCasedWords.
    This filter skips any words matching the following regular expression:

           ^([a-z]\w+[A-Z]+\w+)

    That is, any words that are camelCasedWords.
    """
    _pattern = re.compile(r"^([a-z]+([\d]|[A-Z])(?:\w+)?)")

    def _skip(self, word):
        return bool(self._pattern.match(word))


class SphinxDirectives(Filter):
    r"""Filter skipping over Sphinx Directives.
    This filter skips any words matching the following regular expression:

           ^:([a-z]+):`([^`]+)(`)?

    That is, for example, :class:`BaseQuery`
    """
    # The final ` in the pattern is optional because enchant strips it out
    _pattern = re.compile(r"^:([a-z]+):`([^`]+)(`)?")

    def _skip(self, word):
        return bool(self._pattern.match(word))


class ForwardSlashChunkder(Chunker):
    '''
    This chunker allows splitting words like 'before/after' into 'before' and 'after'
    '''
    def next(self):
        while True:
            if not self._text:
                raise StopIteration()
            if '/' not in self._text:
                text = self._text
                self._offset = 0
                self._text = ''
                return (text, 0)
            pre_text, post_text = self._text.split('/', 1)
            self._text = post_text
            self._offset = 0
            if not pre_text or not post_text or \
                    not pre_text[-1].isalpha() or not post_text[0].isalpha():
                self._text = ''
                self._offset = 0
                return (pre_text + '/' + post_text, 0)
            return (pre_text, 0)

    def _next(self):
        while True:
            if '/' not in self._text:
                return (self._text, 0)
            pre_text, post_text = self._text.split('/', 1)
            if not pre_text or not post_text:
                break
            if not pre_text[-1].isalpha() or not post_text[0].isalpha():
                raise StopIteration()
            self._text = pre_text + ' ' + post_text
        raise StopIteration()


class SpellingChecker(BaseTokenChecker):
    """Check spelling in comments and docstrings"""
    __implements__ = (ITokenChecker, IAstroidChecker)
    name = 'spelling'
    msgs = {
        'C0401': ('Wrong spelling of a word \'%s\' in a comment:\n%s\n'
                  '%s\nDid you mean: \'%s\'?',
                  'wrong-spelling-in-comment',
                  'Used when a word in comment is not spelled correctly.'),
        'C0402': ('Wrong spelling of a word \'%s\' in a docstring:\n%s\n'
                  '%s\nDid you mean: \'%s\'?',
                  'wrong-spelling-in-docstring',
                  'Used when a word in docstring is not spelled correctly.'),
        'C0403': ('Invalid characters %r in a docstring',
                  'invalid-characters-in-docstring',
                  'Used when a word in docstring cannot be checked by enchant.'),
        }
    options = (('spelling-dict',
                {'default' : '', 'type' : 'choice', 'metavar' : '<dict name>',
                 'choices': dict_choices,
                 'help' : 'Spelling dictionary name. '
                          'Available dictionaries: %s.%s.' % (dicts, instr)}),
               ('spelling-ignore-words',
                {'default' : '',
                 'type' : 'string',
                 'metavar' : '<comma separated words>',
                 'help' : 'List of comma separated words that '
                          'should not be checked.'}),
               ('spelling-private-dict-file',
                {'default' : '',
                 'type' : 'string',
                 'metavar' : '<path to file>',
                 'help' : 'A path to a file that contains private '
                          'dictionary; one word per line.'}),
               ('spelling-store-unknown-words',
                {'default' : 'n', 'type' : 'yn', 'metavar' : '<y_or_n>',
                 'help' : 'Tells whether to store unknown words to '
                          'indicated private dictionary in '
                          '--spelling-private-dict-file option instead of '
                          'raising a message.'}),
               ('max-spelling-suggestions',
                {'default': 4, 'type': 'int', 'metavar': 'N',
                 'help': 'Limits count of emitted suggestions for '
                         'spelling mistakes.'}),
              )

    def open(self):
        self.initialized = False
        self.private_dict_file = None

        if enchant is None:
            return
        dict_name = self.config.spelling_dict
        if not dict_name:
            return

        self.ignore_list = [w.strip() for w in self.config.spelling_ignore_words.split(",")]
        # "param" appears in docstring in param description and
        # "pylint" appears in comments in pylint pragmas.
        self.ignore_list.extend(["param", "pylint"])

        # Expand tilde to allow e.g. spelling-private-dict-file = ~/.pylintdict
        if self.config.spelling_private_dict_file:
            self.config.spelling_private_dict_file = os.path.expanduser(
                self.config.spelling_private_dict_file)

        if self.config.spelling_private_dict_file:
            self.spelling_dict = enchant.DictWithPWL(
                dict_name, self.config.spelling_private_dict_file)
            self.private_dict_file = open(
                self.config.spelling_private_dict_file, "a")
        else:
            self.spelling_dict = enchant.Dict(dict_name)

        if self.config.spelling_store_unknown_words:
            self.unknown_words = set()

        self.tokenizer = get_tokenizer(dict_name,
                                       chunkers=[ForwardSlashChunkder],
                                       filters=[EmailFilter,
                                                URLFilter,
                                                WikiWordFilter,
                                                WordsWithDigigtsFilter,
                                                WordsWithUnderscores,
                                                CamelCasedWord,
                                                SphinxDirectives])
        self.initialized = True

    def close(self):
        if self.private_dict_file:
            self.private_dict_file.close()

    def _check_spelling(self, msgid, line, line_num):
        original_line = line
        if line.strip().startswith('#'):
            line = line.strip()[1:]
            starts_with_comment = True
        else:
            starts_with_comment = False
        for word, _ in self.tokenizer(line.strip()):
            lower_cased_word = word.casefold()

            # Skip words from ignore list.
            if word in self.ignore_list or lower_cased_word in self.ignore_list:
                continue

            # Strip starting u' from unicode literals and r' from raw strings.
            if word.startswith(("u'", 'u"', "r'", 'r"')) and len(word) > 2:
                word = word[2:]
                lower_cased_word = lower_cased_word[2:]

            # If it is a known word, then continue.
            try:
                if self.spelling_dict.check(lower_cased_word):
                    # The lower cased version of word passed spell checking
                    continue

                # If we reached this far, it means there was a spelling mistake.
                # Let's retry with the original work because 'unicode' is a
                # spelling mistake but 'Unicode' is not
                if self.spelling_dict.check(word):
                    continue
            except enchant.errors.Error:
                self.add_message('invalid-characters-in-docstring',
                                 line=line_num, args=(word,))
                continue

            # Store word to private dict or raise a message.
            if self.config.spelling_store_unknown_words:
                if lower_cased_word not in self.unknown_words:
                    self.private_dict_file.write("%s\n" % lower_cased_word)
                    self.unknown_words.add(lower_cased_word)
            else:
                # Present up to N suggestions.
                suggestions = self.spelling_dict.suggest(word)
                del suggestions[self.config.max_spelling_suggestions:]

                m = re.search(r"(\W|^)(%s)(\W|$)" % word, line)
                if m:
                    # Start position of second group in regex.
                    col = m.regs[2][0]
                else:
                    col = line.index(word)

                if starts_with_comment:
                    col += 1
                indicator = (" " * col) + ("^" * len(word))

                self.add_message(msgid, line=line_num,
                                 args=(word, original_line,
                                       indicator,
                                       "'{}'".format("' or '".join(suggestions))))

    def process_tokens(self, tokens):
        if not self.initialized:
            return

        # Process tokens and look for comments.
        for (tok_type, token, (start_row, _), _, _) in tokens:
            if tok_type == tokenize.COMMENT:
                if start_row == 1 and token.startswith('#!/'):
                    # Skip shebang lines
                    continue
                if token.startswith('# pylint:'):
                    # Skip pylint enable/disable comments
                    continue
                self._check_spelling('wrong-spelling-in-comment',
                                     token, start_row)

    @check_messages('wrong-spelling-in-docstring')
    def visit_module(self, node):
        if not self.initialized:
            return
        self._check_docstring(node)

    @check_messages('wrong-spelling-in-docstring')
    def visit_classdef(self, node):
        if not self.initialized:
            return
        self._check_docstring(node)

    @check_messages('wrong-spelling-in-docstring')
    def visit_functiondef(self, node):
        if not self.initialized:
            return
        self._check_docstring(node)

    visit_asyncfunctiondef = visit_functiondef

    def _check_docstring(self, node):
        """check the node has any spelling errors"""
        docstring = node.doc
        if not docstring:
            return

        start_line = node.lineno + 1

        # Go through lines of docstring
        for idx, line in enumerate(docstring.splitlines()):
            self._check_spelling('wrong-spelling-in-docstring',
                                 line, start_line + idx)


def register(linter):
    """required method to auto register this checker """
    linter.register_checker(SpellingChecker(linter))
